Sir Peircy Brett (1709 – 14 October 1781) was an officer in the Royal Navy who served on George Anson's voyage around the world, and later rose to the rank of Admiral and lord commissioner of the Admiralty. He was also a Member of Parliament, representing the constituency of Queenborough from 1754 until 1774.
Brett was first lieutenant aboard the HMS Centurion, which became the only vessel to return from Admiral Anson's circumnavigation of the earth between 1740 and 1744.
In late 1738 he had been transferred to Gloucester, one of the ships which sailed under the then Commodore George Anson for the Pacific in September 1740.
On 18 February 1741 Brett was transferred to Anson's own ship, the Centurion, as second lieutenant, and in this capacity on 13 November 1741 he commanded the landing party which sacked and burned the town of Paita. After the capture of the Spanish treasure ship "Nuestra Señora de Covadonga", and following the promotion of Philip Saumarez, Brett became first lieutenant.
Later on 30 September 1743, Anson made him Captain of the Centurion when the commodore had to leave the ship for a time in Canton. Once the party returned to England, on the arrival of the Centurion at Spithead on 15 June 1744 the Admiralty refused to confirm Brett's promotion, though they did give Brett a new commission as captain dated the day the ship anchored. However, on 29 December 1744 the original commission date was confirmed under a new Admiralty of which Anson was a member.
During the Jacobite rising he saw action on the 9 July 1745, when as Captain of HMS Lion he exchanged fire with the French ships Elizabeth and the Du Teillay. The Du Teillay at the time was carrying Charles Edward Stuart to Scotland with supplies and funds to support his cause. The Lion suffered severe damage and had to give up the pursuit and Charles eventually landed at Eriskay.